There has been known a device for detecting linear device values distributed in a matrix. Patent Literature 1, for example, discloses a touch sensor device (contact detecting device) for detecting distribution of capacitance values of a capacitance matrix Cij (i=1, . . . , M and j=1, . . . , L) formed between M drive lines and L sense lines. The touch sensor device operates in accordance with a scanning detection method; specifically, the touch sensor device sequentially selects one of the drive lines and thus detects respective values of linear devices connected to the drive line selected.
Patent Literature 2 discloses a capacitance detecting circuit which (i) in driving a plurality of drive lines, switches between a first drive line group and a second drive line group on the basis of a time series code sequence, (ii) outputs a measured voltage obtained by converting, into an electric signal, a sum total of respective currents across capacitances, connected to sense lines, at a plurality of intersections of driven drive lines with the sense lines, and (iii) performs a product-sum operation of such a measured voltage and the code sequence for each sense line so as to find a voltage value corresponding to a capacitance at each intersection.
As shown in Patent Literature 6, a conventional touch sensor system configured to detect how capacitance values are distributed attempts to carry out recognition of a finger and part of a hand which are in contact with a touch panel, by means of signal processing. For example, assume that a hand holding a stylus is in contact with a touch panel. A signal based on how the touch panel is touched significantly changes over time according to action of moving the stylus etc.
(a) to (d) of FIG. 20 are views for describing touch signals observed when a hand is placed on a touch panel. As shown in (a) of FIG. 20, a region where the hand is placed on the touch panel is small at first, i.e., the region is a region 116a. Then, as shown in (b) of FIG. 20, the region where the hand is placed on the touch panel expands over time to a region 116b. Next, as shown in (c) of FIG. 20, the region where the hand is placed on the touch panel further expands over time, and a tip of a stylus held in the hand makes contact with the touch panel. This causes a stylus input region 118 to appear. After that, as shown in (d) of FIG. 20, the region where the hand is in contact with the touch panel changes from the region 116c to a region 116d, and a region 117 where a finger is in contact with the touch panel appears.